In this guide we will see the main search engines and their characteristics, how they work, simple and advances searches, boolean operators.

SEARCH ENGINES 2

With over a 100 millon web pages, a similar number of newgroups and people receiving e-mail, cyberspace is full of data.

The question is: How do I find what I'm looking for? or where should I begin, even if I am not sure of what I'm looking for?

This can be the hardest part of our experience the cyberspace. It can make us feel joyful and excited when we find something new or what we were looking for, but it can also make us feel tired and frustrated for having lost time without finding anything, and even make us stop wanting to use the computer.

We have an advantage: On the Internet, almost everything is in English, so we won't be stopped by language difficulties.

The main search engines are Yahoo!, Excite, InfoSeek, HotBot, AltaVista, Google, Lycos, Magellan, Open Text, WebCrawler, Inference Find, etc… These are the most visited sites on the Internet. Every one of them usually covers up to 100 million sites in their data base. They offer searches based on statistics and ordered/catalogued by relevance.

What changes from one search engine to another is the way it evaluates, catalogues and presents the search results.

Usually they give us several options by which we can specify our search better. This is the most powerful tool to find something online.

Search engines are diveded into two categories: Directories (or subject guides) and Indexes.

Directories: identify general information. They group sites by category like "French Universities" or "Argentine Rivers".

Indexes: they search for all the contents in a site, not only the name, creating indexes of all the words. They may find sites because they have a page that contains a word we asked for, although the site might have nothing to do with what we are looking for.

Most search on the WWW, UseNet Newsgroups and some of them look for e-mail addresses, company information, FAQ's, etc...

The two types of search are Simple search and Advanced search.

SIMPLE SEARCH

(It is the one we learnt in the previous guide.)

Format: Word (1 Space) Word (1 Space) Word etc...

• They can be one or more words.

• It is convenient to write the most important words first because some search engines pay attention to that.

• It is convenient to write in small caps as this usually produces results in small and all caps. If we write in capital letters it only brings us back results in capital letters.

Eg: wines Argentina Mendoza

Activity I

Try a search using more than one word.

• Write the words in the search box.
  
  
• Click on the search button .

These results are generally more specific than one word searches.

ADVANCED SEARCH

This depends to the search engine as they have all developed different tools to specify the search. These are some of the most common ways of specifying the search.

Format: Word +Word

By adding a + sing before the word (without leaving a space) specifies which words must appear in the results.

It can be done with multiple words.

Ex: +police +sting (will give us results of the band)

Format: Word -Word

Adding a - sing before the word (without leaving a space) specifies which words must not appear in the results.

This can me done with multiple words.

Ex: +sting -police (will produce results of the solo musician, a fighter, a football team, etc...)

Format: "Word Word Word"

Writing a group of words between inverted comas tranforms it into a phrase. The browser will look for this exact combination of words only.

It is usually used for names.

We can combine phrases and words in a search query.

Eg: "american constitution" (will only show us results of this, without pages referring to the country or the physical constitution, etc.)

BOOLEAN OPERATORS

Boolean operators allow us to specify our search even more by using the terms AND, AND NOT, OR and brackets. These operators must appear in capital letters and with a space on each side to work. They specify exactly which words we want to appear or not. (Some search engines use it in a different way).

AND: contains both terms.
For example if we want to search siamese cats we can write cats AND siamese.

OR: contains one term or the other.
If we want something about laptops but we know they could also appear as notebooks we would write laptops OR notebooks.

AND NOT: (sometimes used as BUT NOT) contains one term but not the other.
In order to see pets but not dogs we have to write pets AND NOT dogs.

Brackets: We can also use brackets to define the search.
For a search on fruits and specially on bananas and apples we need to write fruit AND (banana OR apple).

Activity II

Try some advance searches to see if you can refine your search.

Some main search engines and their characteristics.

www.yahoo.com (Directory)
Yahoo! editors have catalogued millons of web sites in what they call Categories (or subjects). Yahoo! is very useful when we are looking for general information on a subject.

First it presents us with links within it's categories and then with links for web sites.

www.hotbot.com (Index)

It looks for the words we entered, not their meaning. You will find that all the sites contain the word/words you entered. It is one of the biggest in the Net. It has filters for advanced searching which are easy to use.

www.webcrawler.com (Index)
It looks for the words we entered, not their meaning. The site may be unrelated to what we are looking for as long as the search term is there. Usually produces a long list to be filtered.

www.lycos.com (Index)
Lycos analyses every site and it's links on the Web. It looks for words, not phrases. It can also look by subject. It has an advanced search (personalized) at this address http://www-es.lycos.com/assist-es/pages/customsearch.html

www.go.com

It searches for images, video, etc.
Very good performance in general.

www.altavista.com (Index)

It offers the great control for specifying the search.
It may be the most powerful search engine on the Web with the most powerful access to web pages. It allows search by language which helps people who don't speak English.

Google
Cute and very powerful.

MonkeySweat
Apparantly very fast and with a large number of indexed pages.

www.excite.com (Index)

Tips:

• Specify which words must appear in the results by adding a + sing before the word (without leaving a space)
  
  
• Specify which words must not appear in the results by adding a - sing before the word (without leaving a space)

Boolean Operators with some search engines

Boolean Operators allow us to specify our search even more. In some of them we can use AND, AND NOT, OR y paréntesis. These operators must appear in capital letters and with a space on each side in order to work. They specify exactly which words we want to appear or not.